David gave a demo of his soon to be released Retrospective Tool (thanks David!)

We discussed which exercises would be suitable for remote/distributed retrospectives, the conclusion was that almost all exercises can be used in such a setting. It depends however on the skills of the facilitator who should be capable enough to manage a retrospective that is ongoing in multiple locations.

Luis Gonçalves wrote a blog post 21 Mandatory Tools for Distributed Agile Retrospectives which provides information on tools.

Ben Linders maintains a Retrospectives Exercises webpage which also contains exercises that are suitable for remote/distributed retrospectives.